transmission slipping - PeachParts Mercedes-Benz Forum

Mark in NJ · #1 08-09-2006, 09:34 PM

For starters, the car is a 1983 300cd turbo 265,000 miles. Transmission repair history unknown. Ive had the car for about 20,000 miles and 18 months.

On my way home today in slow stop go traffic, the engine started to rev faster but the car go slower. I gently feathered the gas to keep it moving but not press it too hard so it would rev. I pulled over, In Newark NJ of all places. I put it in park, shut-off the car and poped the hood. The tranny fluid was there on the dipstick, and nice and red, the only wierd thing was that there were a few tiny air bubbles on the dipstick. (not foam, like maybe 6 little bubbles)

So, I closed the hood and tried driving again, This time it was fine for a while, started to give a hint of slipping, so I put it in neutral and coasted for a few seconds, then back in drive. I made it the rest of the way home without a hitch (no pun intended, but dam that is funny

)

Anyway, I will check this forum in the morning and you all can tell me if I should take it to work again, or use the minivan.

Buy a new tranny, or just adjust some stupid vacuum hose or something..

TMAllison · #2 08-09-2006, 10:58 PM

twp things you can do.

adjust the modulator in 1/8 or 1/4 turns on the side of the tranny to increase pressure (and hardness of shifts).

or(and)

adjust the nylon throttle cable on top of the valve cover to delay/retard shift points.

Lycoming-8 · #3 08-09-2006, 11:46 PM

It is imperative that the tranny fluid level be checked in park with the car level and the engine running. Should also be done after getting the engine and tranny fluid warmed up. From your description it appears that the level was checked with the engine off. This will result in inaccurate readings.

Gary F. · #4 08-10-2006, 11:37 AM

The fluid should be changed every 30000 miles. Since you don't know the history, now is the time to change it out. Remember to drain torque converter also. Check fluid using a white paper towel, it should be a light pink in color on the paper towel (for future reference). I pull the drain plug on my transmission every 3rd oil change, and add new fluid., good insurance and only costs about $6.00 in transmission fluid, compared to a $1800 rebuild.

Hope this helps. Good luck on your project.

Mismost · #5 08-10-2006, 12:36 PM

Another simple and cheap thing to do is replace all the under hood vaccum connectors....they are 23 years, dried out, cracked...just put on all new ones.

If your EGR is still hooked up, it seems to be a prime source of problems, vaccum related, that can effect the transmission's operation. Mine flared very bad when I bought the car...renewed all the vac connections, blocked off the EGR, changed tranny fluid and filter..car shifts real good now. It may not be one major item, but a combination of lots of small items. It was a about a 30 dollar total on mine.

Lots of information on the EGR removal or blocking plate on this site.

ConnClark · #6 08-11-2006, 11:38 AM

A plugged or dirty transmission filter on these cars is notorious for causing the transmission to slip.

My transmission started slipping right after I bought my 85 300SD. Being that it was the dead of winter I tried to get a kwiki lube to replace the filter and fluid. Unfortunatly they said they don't replace filters any more, they do power flushes. So I opted for a power flush and a fluid change. That stopped my car from slipping until it was warm enough to change the filter and fluid myself.

My transmission doesn't slip anymore.